Some motors are designed to use coils in order to generate a magnetic field. These motors include two sets of coils, one located in the stator and one located in the rotor. One set of coils is energized using conductive contacts or brushes that may touch on the shaft or the moving body. The current fed to these coils creates an electromagnetic field. Other motors and generators employ permanent magnets to provide motion. Electricity is produced when coils of copper windings are moved relative to the flux fields generated by the magnets. Alternatively, electricity may be fed into the coils to produce motion. In both of these scenarios, separate bearings are used to define the relative motion between the coils and magnets, which may be linear or rotary in nature. In either case, the flux field creates an attractive force that must be resisted by the bearings. This force is mitigated in some degree when there is an opposing force applied at 180° from other magnets. Although the opposing force mitigates the flux field's attractive force, it is not a stabilizing force. For example, as the coils get closer to the magnets on one side, the attractive force from those magnets increase, which moves the coils further away from the magnets that are arranged at 180° and decreases the applied opposing force. In the absence of separate bearings, the coils and magnets would come into contact and disable the motor or generator's function.
Permanent magnet motors employ magnets made of, for example and without limitation, neodymium NdFeB or ferrite. There are multiple methods for manufacturing these magnets, such as through casting in a mold, pressing, injection molding, or bonding. In most cases, these magnets are porous, which is especially true for magnets that are sintered. These magnets may be magnetized after they have been formed into their desired shape. Motors and generators may employ a wide variety of magnetic circuit designs. Permanent magnets may be used on the outside diameter of a rotating body or on the interior of a housing. They may use switched reluctance or induction and may use AC or DC current.
Motors and generators' efficiency and power can be increased by minimizing the distance between the coils in the magnets. As the distance between the coils decreases, the flux field force increases. However, due to the unstable relationship between the coils and magnets as described above, relatively large gaps between coils must be used in the manufacture of motors and generators. Such an arrangement is shown by U.S. Pat. No. 5,036,235 to Klecker.
Design engineers have been trying to achieve more functionality in less space. The paradigm today in the design of motors and generators is to have separate bearings and motor functions. This results in assemblies that are longer, larger in diameter, and heavier than if the motor and bearing elements can be one in the same. For example, see the assembly shown by U.S. Pat. No. 5,443,413 to Pflager et al.
In U.S. Pat. No. 5,098,203 to Henderson, magnets are inserted into the face of a hydrostatic bearing assembly in order to increase the stiffness of the hydrostatic film with the magnets' preload force. However, there is no disclosure of using such magnets in a motor or generator.
One of ordinary skill in the art of hydrostatic bearings would appreciate that air and other gases are examples of a fluid used in hydrostatic bearings. This means that the broad term of hydrostatic bearings encompasses aerostatic bearings, as discussed in U.S. Pat. No. 5,488,771 to Devitt et al. The terms “hydrostatic bearings” and “hydrodynamic bearings” are both encompassed in the definition of “fluid film bearings.” Hydrostatic bearings are differentiated from hydrodynamic bearings by the use of an external pressure source, which allows hydrostatic bearings to operate even with zero velocity between the relative bearing faces. In contrast, hydrodynamic bearings require relative motion between bearing faces to create fluid film pressure. One of ordinarily skill in the art would also appreciate that hydrostatic bearings exhibit hydrodynamic effects when there is relative motion between the bearing faces. These hydrodynamic effects are an unavoidable result of the shear of the hydrostatic fluid caused by the relative motion of the bearing surfaces, and are included in the operation of hydrostatic bearings.
Accordingly, it is an object of the present application to combine the bearing and motor functionalities, provide economy of space, and improve efficiency by reducing the gap in the flux field to the thickness of the hydrostatic bearing fluid.